Physico-chemical and microbial processes governing the decay of organic substance in sediment under anoxic conditions

缺氧条件下控制沉积物中有机物质腐烂的物理化学和微生物过程

• 批准号: 396708702
• 负责人: Professor Dr. Christian Gerhard Ballhaus
• 金额: --
• 依托单位: Abteilung Paläontologie
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/396708702?language=en
• 关键词: Physico; chemical; microbial; processes; governing

To fossilize soft tissue of marine taxa it is essential that a carcass be transferred rapidly to anoxic conditions and isolated from potential scavengers. A practical way to achieve this is by burying a decaying carcass or a living sessile species in sediment. The oxidation of organic carbon to HCO3- and CO32- within the sediment will reduce the major electron acceptors in sediment and seawater, i.e. ferric iron and sulfate. The decay reactions will create local Eh and pH haloes around a carcass within which FeS sulfide, siderite, and other carbonate phases may be stabilized. These phases may then replace or template organic tissue, or encase the organic material in concretions. Within the research unit FOR 2685 the applicant will develop experimental routines that allow to investigate in-situ the anoxic decay of fish and echinoderms within a marine sediment. The major aim is to quantify the rates by which replacement can take place. While an experiment is progressing, organic material will be sampled from time to time. Inorganic precipitates will be identified by Raman spectroscopy. Bacterial communities emerging will be characterised in close collaboration with members of the research unit. It is expected that the templation by inorganic material - FeS phases, siderite, calcite - may be a matter of weeks to months. The characterisation of bacterial communities, an important aspect in the present proposal, will elucidate if pseudomorphic replacement reaction are inorganic by nature and driven only by pH and Eh gradients, or if they must be mediated by bacteria in order to be efficient.

为了使海洋生物的软组织腐烂，必须将尸体迅速转移到缺氧条件下，并与潜在的清道夫隔离。实现这一目标的一个实际方法是将腐烂的尸体或活着的固着物种埋在沉积物中。有机碳在沉积物中氧化为HCO 3-和CO 32-，会还原沉积物和海水中的主要电子受体，即三价铁和硫酸盐。衰变反应将在骨架周围产生局部Eh和pH晕，其中FeS硫化物、菱铁矿和其他碳酸盐相可以稳定。然后这些相可以替代或模板化有机组织，或将有机材料包裹在结核中。在FOR 2685研究单元内，申请人将开发实验程序，以便现场调查海洋沉积物中鱼类和棘皮动物的缺氧腐烂。主要目的是量化替代率。在实验进行期间，将不时对有机材料进行取样。无机沉淀物将通过拉曼光谱法鉴定。将与研究单位的成员密切合作，对出现的细菌群落进行表征。预计无机材料- FeS相、菱铁矿、方解石-的模板化可能是几周到几个月的事情。细菌群落的表征，在本提案中的一个重要方面，将阐明，如果假晶置换反应是无机的性质和驱动的pH值和Eh梯度，或者如果他们必须介导的细菌，以有效的。